1. Field of the Invention
The present invention relates to a vibration reduction apparatus suitable to prevent an image from blurring due to an unintentional movement of a hand in using a camera, and more particularly to a vibration reduction apparatus having a vibration detecting means with an improved built-in structure that detects the movement of a camera. The present invention also relates to a vibration reduction apparatus that allows a vibration detecting means and a vibration reduction mechanism to be readily adjusted to a desired positional interrelationship.
2. Related Background Art
Current cameras have been sophisticatedly automated and particularly the various sections including the auto-exposure mechanism and the auto-focus mechanism have been remarkably converted into electronic form. However, this kind of camera still includes insufficiently automated sections. Countermeasures against an image blur that occurs due to movement of hands in manually taking a photograph have been tried for a long time.
In order to prevent an image blur due to movement of a camera, particularly, tilt or vibration of a camera, cameras with vibration reduction devices are well-known conventionally. The vibration reduction device detects vibration of a camera using a vibration detecting means such as an acceleration sensor and a vibration sensor, and shifts the photographing lens system (main optical system) or the partial optical system acting as a vibration reduction optical system (vibration reduction lens) in the direction perpendicular to the optical axis in accordance with the resultant detection.
In a camera with the vibration reduction function, the vibration reduction optical system (hereinafter, referred to a vibration reduction lens) forming at least a part of a photographing lens system is movably supported. In order to cancel the image blur, the shift of an image on a film surface due to vibration is corrected by shifting or moving in the vibration absorbing direction over the surface perpendicular to the optical axis of the main optical system, in accordance with the vibration of a camera detected by means of the vibration detecting means.
The vibration reduction device having the drive mechanism to shift the vibration reduction lens is disclosed in Japanese Patent Application Laid-Open No. 3-110530.
In this prior-art structure, the lens frame for the vibration reduction lens is movably held in the plane perpendicular to the optical axis, and the vibration reduction lens is directly driven and traveled by effecting the drive force acting as a push force and stretching force of the drive means (such as motor, gear chain, lever or screw shaft, ball, and V-shape groove) on the lens frame via a connecting means (such as a rod member or drive shaft).
In order to construct such a vibration reduction apparatus, it is necessary to build a vibration detecting sensor, or a camera vibration detecting means, inside a camera.
In Japanese Patent Application Laid-Open No. 5-61091, the present applicant proposed a camera where a vibration detecting sensor such as an acceleration sensor or vibration gyroscope for a vibration detection is arranged in either a space between the outer wall of the spool room and the photographing lens barrel or a camera obscura or a space between the outer wall of the film cartridge room and the photographing lens barrel or camera obscura, whereby the internal space of the camera can be effectively used.
That is, the camera body is formed of two sections: a rear body including a film cartridge room, a spool room, an aperture, a camera obscura, and the like and a front body including a photographing lens barrel and the like. This prior art structure is adopted in consideration of an easiness to assemble elements into the rear body because it is desired to arrange the vibration detecting sensor inside a camera because of the assembly convenience.
According to the structure, the internal space of a camera, and particularly the dead space in the rear body, is utilized cleverly and the vibration detecting sensor can be assembled simply and suitably in a camera without leading to a large-size of a camera.
However, according to the above-mentioned prior art, the vibration detecting sensor built-in the rear body of a camera body causes essentially the following disadvantages.
The vibration reduction lens, which constitutes a part of the photographing lens, is built in the front body. As described above, the mechanism shift-driving the lens is arranged in the front body while the vibration detecting sensor is built in the rear body.
The problem is that it is necessary to match the sensitivity axis of the vibration detecting sensor with the shift axis of the vibration reduction lens to achieve the vibration reduction effect with good accuracy.
In the prior art, the vibration reduction lens is built in the front body while the vibration detecting sensor is built in the rear body. The prior art structure makes it impossible to adjust the sensitivity axis of the vibration detecting sensor after the front body has been assembled in the rear body. Hence, there has been a disadvantage in that it is impossible actually to match the direction of the shift axis of the vibration reduction lens with that of the sensitivity axis of the vibration detecting sensor.
If such a positional shift occurs, it is necessary to disassemble again the front and rear bodies and then to reassemble them over an adjusting work so as to positionally matched them. It has been impossible to avoid the problem that the assembling work is troublesome and complicated.
Particularly, in order to obtain the vibration reduction function, it is important to align and adjust the vibration reduction lens or the drive mechanism with the vibration detecting sensor. It has been desired long to take a countermeasure that can solve the above-mentioned problems.
Furthermore, according to the prior-art structure, it has been impossible to remove the positional shift and the directional shift which are caused by the backlash or play between the lens barrel with a vibration reduction lens and the rear body of a camera with a vibration detecting sensor.
Particularly, the vibration reduction lens arranged in the lens barrel is movably held by combining together the drive control unit, a fixture barrel such as a straight guide barrel and a cam barrel, and a movable barrel. It is impossible to avoid the play or loose tolerance due to the processing accuracy and assembling accuracy of the components as well as the movable connecting means. Hence, it has been impossible actually to adjust the position between the vibration reduction lens and the vibration detecting sensor in a desired state.
Therefore, since the prior art vibration reduction apparatus has advantages and disadvantages, it has been desired for a long time to take a countermeasure that can solve the above-described problems.
However, there has been a disadvantage in that where the prior-art vibration reduction lens barrel includes angular velocity sensors as vibration sensors that detect respectively an angular velocity around the horizontal axis (X-axis) and an angular velocity around the vertical axis (Y-axis), it takes much time to adjust the position of the optical axis of each angular velocity sensor. Also, there has been a problem in that it is difficult to register with good accuracy each angular sensor with respect to the upper and lower portion of a camera body.
Moreover, there has been a problem in that it takes a great deal of time to align the sensitivity direction of the angular velocity sensor with the drive direction of the vibration reduction mechanism in which the vibration reduction optical system moves in the directions of the X-axis and Y-axis.
In order to position accurately the sensitivity direction of the angular velocity sensor, it is desired that the angular velocity sensor is arranged, as possible, adjacent to the lens mount at the reference position of the lens barrel so that the accumulated error becomes small. However, there has been a problem in that since the diaphragm and the AF drive transmission unit are in an arranged state, a sufficient space cannot be ensured.